Optical duobinary transmission system featuring improved receiver sensitivity and reduced optical bandwidth

We propose and demonstrate a simple method to improve both the receiver sensitivity and spectral efficiency of the optical duobinary transmission system. Compared to the conventional duobinary signal generated by using an electrical low-pass filter, more than 1-dB improvement of receiver sensitivity and /spl sim/20% reduction in the spectral width are achieved simply by filtering the 10-Gb/s duobinary signals with a narrow-bandwidth (7 GHz) optical filter.